There are several possibilities:
dotEPUB:
http://dotepub.com/ (seriously, this is the first link found in google when entering dotepub. How you couldn't find it eludes me)
pocket articles can be converted using calibres fetch news feature, there is a recipe for it
Push to kindle:
http://fivefilters.org/kindle-it/ despite the name it also supports epub
Readability:
https://www.readability.com/
and I think there are even more. All of the above have a firefox extension.